Introductıon
Wilms’ tumor is one of the most common childhood solid malignancies,
which accounts for almost 95% of renal malignancies in pediatrics, and
classically arises from primitive metanephric cells. Exceptionally it
may occur at places other than kidneys. The occurrence of nephroblastoma
outside the kidneys in the absence of a primary renal tumor is known as
the extrarenal Wilms tumor (ERWT). ERWT is an uncommon entity that was
first described by Moyson et al. in 1961(1). The estimated rate of
nephroblastoma outside the kidneys is almost 0.5 to 1% of Wilms’ tumor
cases. Extrarenal Wilms’ tumor occurs mostly in childhood; however, it
is also rarely reported in adults (2) that typically involves the
embryonic path of the developing kidneys and gonads. Apart from the
primary ERWT, nephroblastoma may be observed outside the kidneys in two
other situations: metastatic disease and nephroblastoma arising in a
teratoma; therefore, in the case of ERWT, it is mandatory to evaluate
the kidneys for primary tumor preoperatively and search the whole
specimen for any teratoid element postoperatively (3).
The most widely accepted hypothesis for the pathogenesis of ERWT
suggests that the ectopic nephrogenic rest develops into a
nephroblastoma. It is well known that the persistent intrarenal fetal
nephrogenic blastemal tissue may undergo oncogenic mutation and develop
nephroblastoma. Several reports pointed to the observation of ectopic
nephrogenic rests, especially in inguinal or retroperitoneal and
lumbosacral regions (4).
In this article, we report a 3-year-old girl who first presented with
spinal dysraphism and a mass in the lumbar spinal cord with a
histopathological diagnosis of nephrogenic rest, and after one year, a
Wilms tumor arose in this location. ERWT is an unusual entity that
typically involves the embryonic path of the developing kidneys and
gonads. ERWT located in the spine is unlikely to be suspected
preoperatively because it is embryologically less intuitive. Thus, we
report this case of a congenital Wilms tumor associated with spinal
dysraphism to increase awareness and describe this malignant tumor’s
clinical outcome.